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1.
Gold(I)‐Catalyzed Desymmetrization of 1,4‐Dienes by an Enantioselective Tandem Alkoxylation/Claisen Rearrangement
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Hongmiao Wu Dr. Weiwei Zi Prof. Dr. Guigen Li Prof. Dr. Hongjian Lu Prof. Dr. F. Dean Toste 《Angewandte Chemie (International ed. in English)》2015,54(29):8529-8532
An enantioselective alkoxylation/Claisen rearrangement reaction was achieved by a strategic desymmetrization of 1,4‐dienes under the catalysis of (S)‐DTBM‐Segphos(AuCl)2/AgBF4. This reaction system was highly selective for the formation of 3,3‐rearrangement products, providing cycloheptenes with various substitutions in good yield and good to excellent enantioselectivity. This transformation was further extended to bicyclic ring substrates, providing the opportunity to easily assemble 5,6‐ and 6,7‐fused ring systems. 相似文献
2.
Palladium‐Catalyzed Enantioselective Desymmetrizing Aza‐Wacker Reaction: Development and Application to the Total Synthesis of (−)‐Mesembrane and (+)‐Crinane
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Dr. Xu Bao Dr. Qian Wang Prof. Dr. Jieping Zhu 《Angewandte Chemie (International ed. in English)》2018,57(7):1995-1999
Reported is an unprecedented catalytic enantioselective desymmetrizing aza‐Wacker reaction. In the presence of a catalytic amount of a newly developed Pd(CPA)2(MeCN)2 catalyst (CPA=chiral phosphoric acid), a pyrox ligand, and molecular oxygen, cyclization of properly functionalized prochiral 3,3‐disubstituted cyclohexa‐1,4‐dienes afforded enantioenriched cis‐3a‐substituted tetrahydroindoles in good yields with excellent enantioselectivities. A cooperative effect between the phosphoric acid and the pyrox ligand ensured efficient transformation. This reaction was tailor‐made for Amaryllidaceae and Sceletium alkaloids as illustrated by its application in the development of the concise and divergent total synthesis of (?)‐mesembrane and (+)‐crinane. 相似文献
3.
Dipl.‐Chem. Tanja Kanzian Dr. Simona Nicolini Dr. Lucia De Crescentini Prof. Dr. Orazio A. Attanasi Dr. Armin R. Ofial Prof. Dr. Herbert Mayr 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(39):12008-12016
The kinetics of the reactions of 1,2‐diaza‐1,3‐dienes 1 with acceptor‐substituted carbanions 2 have been studied at 20 °C. The reactions follow a second‐order rate law, and can be described by the linear free energy relationship log k(20 °C)=s(N+E) [Eq. (1)]. With Equation (1) and the known nucleophile‐specific parameters N and s for the carbanions, the electrophilicity parameters E of the 1,2‐diaza‐1,3‐dienes 1 were determined. With E parameters in the range of ?13.3 to ?15.4, the electrophilic reactivities of 1 a–d are comparable to those of benzylidenemalononitriles, 2‐benzylideneindan‐1,3‐diones, and benzylidenebarbituric acids. The experimental second‐order rate constants for the reactions of 1 a – d with amines 3 and triarylphosphines 4 agreed with those calculated from E, N, and s, indicating the applicability of the linear free energy relationship [Eq. (1)] for predicting potential nucleophilic reaction partners of 1,2‐diaza‐1,3‐dienes 1 . Enamines 5 react up to 102 to 103 times faster with compounds 1 than predicted by Equation (1), indicating a change of mechanism, which becomes obvious in the reactions of 1 with enol ethers. 相似文献
4.
Silke Erfle Sebastian Reimann Alina Bunescu Zharylkasyn A. Abilov Anke Spannenberg Peter Langer 《Helvetica chimica acta》2012,95(6):1037-1047
The TiCl4‐mediated [3+3] cyclocondensation of various 1,3‐bis(trimethylsilyloxy)buta‐1,3‐dienes with 1‐chloro‐1,1‐difluoro‐4‐(trimethylsilyloxy)pent‐3‐en‐2‐one provides a regioselective access to novel 6‐(chlorodifluoromethyl)salicylates (=6‐(chlorodifluoromethyl)‐2‐hydroxybenzoates) with very good regioselectivity. For selected products, it was demonstrated that the CF2Cl group can be transformed to CF2H and CF2(Allyl) by free‐radical reactions. 相似文献
5.
Highly Diastereo‐ and Enantioselective Cu‐Catalyzed Borylative Coupling of 1,3‐Dienes and Aldimines
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Liyin Jiang Prof. Dr. Peng Cao Dr. Min Wang Bin Chen Bing Wang Prof. Dr. Jian Liao 《Angewandte Chemie (International ed. in English)》2016,55(44):13854-13858
A Cu‐catalyzed diastereo‐ and enantioselective borylative coupling reaction of 1,3‐dienes with imines was realized. Branched homoallylic amines are readily prepared in a syn‐selective manner with high regio‐, diastereo‐ and enantioselectivity. Moreover, these three‐component coupling reactions feature good functional‐group compatibility and easy access to the substrates and catalyst. 相似文献
6.
A study aimed at developing an enantioselective synthesis of the title compound 23 , a 2‐monodeoxy analogue of the naturally occurring (+)‐2‐keto‐3‐deoxy‐D ‐glycero‐D ‐galacto‐2‐nononic acid (KDN), is reported. From D ‐mannose as starting material, the chiral 1,3‐diene 10 , activated by a silyloxy substituent at C(2), was prepared in six steps (Scheme 1). However, the intermediates were often contaminated with varying amounts of by‐products arising from overoxidation during cleavage with periodic acid. An alternative route starting from the inexpensive and readily available D ‐isoascorbic acid ( 12 ), though a little longer than the first, satisfactorily circumvented the purification problem and led to the desired dienes 17 in good yields (scheme 2). The [CoII(S,S)‐(+)‐salen]‐catalyzed hetero‐Diels‐Alder reactions of the aforementioned dienes with ethyl glyoxylate proceeded smoothly at room temperature, giving the dihydropyrano adducts 18 in moderate yields (Scheme 3). Dihydroxylation of 18a followed by reduction of the keto function gave the desired 4,5‐trans dihydroxy moiety of the KDN framework (Scheme 4, see 21 ). The spectroscopic data of the penta‐O‐acetylated 2‐deoxy‐KDN ethyl ester 23 were consistent with those reported for the corresponding methyl ester derived from natural KDN. 相似文献
7.
Muftah M. Basher Yuri E. Corilo Regina Sparrapan Mario Benassi Rodinei Augusti Marcos N. Eberlin José M. Riveros 《Journal of mass spectrometry : JMS》2012,47(11):1526-1535
Gas‐phase reactions of model carbosulfonium ions (CH3‐S+ = CH2; CH3CH2‐S+ = CH2 and Ph‐S+ = CH2) and an O‐analogue carboxonium ion (CH3‐O+ = CH2) with acyclic (isoprene, 1,3‐butadiene, methyl vinyl ketone) and cyclic (1,3‐cyclohexadiene, thiophene, furan) conjugated dienes were systematically investigated by pentaquadrupole mass spectrometry. As corroborated by B3LYP/6‐311 G(d,p) calculations, the carbosulfonium ions first react at large extents with the dienes forming adducts via simple addition. The nascent adducts, depending on their stability and internal energy, react further via two competitive channels: (1) in reactions with acyclic dienes via cyclization that yields formally [4 + 2+] cycloadducts, or (2) in reactions with the cyclic dienes via dissociation by HSR loss that yields methylenation (net CH+ transfer) products. In great contrast to its S‐analogues, CH3‐O+ = CH2 (as well as C2H5‐O+ = CH2 and Ph‐O+ = CH2 in reactions with isoprene) forms little or no adduct and proton transfer is the dominant reaction channel. Isomerization to more acidic protonated aldehydes in the course of reaction seems to be the most plausible cause of the contrasting reactivity of carboxonium ions. The CH2 = CH‐O+ = CH2 ion forms an abundant [4 + 2+] cycloadduct with isoprene, but similar to the behavior of such α,β‐unsaturated carboxonium ions in solution, seems to occur across the C = C bond. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
8.
The 1,3‐dipolar cycloaddition reactions of 2‐diazocyclohexane‐1,3‐dione ( 7a ; Table 1) and of alkyl diazopyruvates ( 11a – e ; Table 3) to 2,3‐dihydrofuran and other enol ethers have been investigated in the presence of chiral transition metal catalysts. With RhII catalysts, the cycloadditions were not enantioselective, but those catalyzed by [RuIICl2( 1a )] and [RuIICl2( 1b )] proceeded with enantioselectivities of up to 58% and 74% ee, respectively, when diazopyruvates 11 were used as substrates. The phenyliodonium ylide 7c yielded the adduct 8a in lower yield and poorer selectivity than the corresponding diazo precursor 7a (Table 2) upon decomposition with [Ru(pybox)] catalysts. This suggests that ylide decomposition by RuII catalysts, contrary to that of the corresponding diazo precursors, does not lead to Ru‐carbene complexes as reactive intermediates. Our method represents the first reproducible, enantioselective 1,3‐cycloaddition of these types of substrates. 相似文献
9.
M. Sc. Vincent Eschenbrenner‐Lux Dipl.‐Biol. Philipp Küchler Dr. Slava Ziegler Dr. Kamal Kumar Prof. Herbert Waldmann 《Angewandte Chemie (International ed. in English)》2014,53(8):2134-2137
The imino Diels–Alder reaction is an efficient method for the synthesis of aza‐heterocycles. While different stereo‐ and enantioselective inverse‐electron‐demand imino Diels–Alder (IEDIDA) reactions have been reported before, IEDIDA reactions including electron‐deficient dienes are unprecedented. The first enantioselective IEDIDA reaction between electron‐poor chromone dienes and cyclic imines, catalyzed by zinc/binol complexes is described. The novel reaction provides a facile entry to a natural product inspired collection of ring‐fused quinolizines including a potent modulator of mitosis. 相似文献
10.
Formation of Tri‐ and Tetranuclear Titanacycles through Decamethyltitanocene‐Mediated Intermolecular C–C Coupling of Dinitriles
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Dr. Lisanne Becker Dr. Perdita Arndt Dr. Anke Spannenberg Dr. Haijun Jiao Prof. Dr. Uwe Rosenthal 《Angewandte Chemie (International ed. in English)》2015,54(18):5523-5526
The reactions of [Cp*2Ti(η2‐Me3SiC2SiMe3)] (Cp*=η5‐pentamethylcyclopentadienyl) with various dicyano compounds were investigated. Nitrile–nitrile C? C couplings result in multinuclear complexes owing to the bifunctionality of the substrates. Applying 1,3‐ or 1,4‐dicyanobenzene led to tri‐ and tetranuclear complexes of the rare 1‐metalla‐2,5‐diaza‐cyclopenta‐2,4‐dienes. These are potential catalysts and were tested in the ring‐opening polymerization of ε‐caprolactone. The reaction with adiponitrile as alkyl dinitrile afforded a trinuclear 1‐metalla‐2,5‐diaza‐cyclopent‐3‐ene through additional protonation of the nitrogen atoms. The structure and bonding of the products were investigated by X‐ray crystallography and DFT analysis to understand the molecular organization in the macrocycles. 相似文献
11.
Qing‐Xia Zhang Yao Li Jie Wang Chen Yang Cheng‐Jun Liu Xin Li Jin‐Pei Cheng 《Angewandte Chemie (International ed. in English)》2020,59(11):4550-4556
The enantioselective ketimine–ene reaction is one of the most challenging stereocontrolled reaction types in organic synthesis. In this work, catalytic enantioselective ketimine–ene reactions of 2‐aryl‐3H‐indol‐3‐ones with α‐methylstyrenes were achieved by utilizing a B(C6F5)3/chiral phosphoric acid (CPA) catalyst. These ketimine–ene reactions proceed well with low catalyst loading (B(C6F5)3/CPA=2 mol %/2 mol %) under mild conditions, providing rapid and facile access to a series of functionalized 2‐allyl‐indolin‐3‐ones with very good reactivity (up to 99 % yield) and excellent enantioselectivity (up to 99 % ee). Theoretical calculations reveal that enhancement of the acidity of the chiral phosphoric acid by B(C6F5)3 significantly reduces the activation free energy barrier. Furthermore, collective favorable hydrogen‐bonding interactions, especially the enhanced N?H???O hydrogen‐bonding interaction, differentiates the free energy of the transition states of CPA and B(C6F5)3/CPA, thereby inducing the improvement of stereoselectivity. 相似文献
12.
Reactivity Study of Pyridyl‐Substituted 1‐Metalla‐2,5‐diaza‐cyclopenta‐2,4‐dienes of Group 4 Metallocenes
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Dr. Lisanne Becker Dr. Fabian Reiß Dr. Kai Altenburger Dr. Anke Spannenberg Dr. Perdita Arndt Dr. Haijun Jiao Prof. Dr. Uwe Rosenthal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(31):10826-10838
In this work the reactivity of 1‐metalla‐2,5‐diaza‐cyclopenta‐2,4‐dienes of group 4 metallocenes, especially of the pyridyl‐substituted examples, towards small molecules is investigated. The addition of H2, CO2, Ph?C≡N, 2‐py?C≡N, 1,3‐dicyanobenzene or 2,6‐dicyanopyridine results in exchange reactions, which are accompanied by the elimination of a nitrile. For CO2, a coordination to the five‐membered cycle occurs in case of Cp*2Zr(N=C(2‐py)?C(2‐py)=N). A 1,4‐diaza‐buta‐1,3‐diene complex is formed by H‐transfer in the conversion of the analogous titanocene compound with CH3?C≡N, PhCH2?C≡N or acetone. For CH3?C≡N a coupling product of three acetonitrile molecules is established additionally. In order to split off the metallocene from the coupled nitriles, we examined reactions with HCl, PhPCl2, PhPSCl2 and SOCl2. In the last case, the respective thiadiazole oxides and the metallocene dichlorides were obtained. A subsequent reaction produced thiadiazoles. 相似文献
13.
Tobias Pinkert Tristan Wegner Shobhan Mondal Frank Glorius 《Angewandte Chemie (International ed. in English)》2019,58(42):15041-15045
A protocol for the three‐component 1,4‐carboamination of dienes is described. Synthetically versatile Weinreb amides were coupled with 1,3‐dienes and readily available dioxazolones as the nitrogen source using [Cp*RhCl2]2‐catalyzed C?H activation to deliver the 1,4‐carboaminated products. This transformation proceeds under mild reaction conditions and affords the products with high levels of regio‐ and E‐selectivity. Mechanistic investigations suggest an intermediate RhIII–allyl species is trapped by an electrophilic amidation reagent in a redox‐neutral fashion. 相似文献
14.
Reversal of the Regiochemistry in the Rhodium‐Catalyzed [4+3] Cycloaddition between Vinyldiazoacetates and Dienes
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Dr. Pablo E. Guzmán Dr. Yajing Lian Prof. Dr. Huw M. L. Davies 《Angewandte Chemie (International ed. in English)》2014,53(48):13083-13087
A regio‐, diastereo‐, and enantioselective [4+3] cycloaddition between vinylcarbenes and dienes has been achieved using the dirhodium tetracarboxylate catalyst [Rh2(S‐BTPCP)4]. This methodology provides facile access to 1,4‐cycloheptadienes that are regioisomers of those formed from the tandem cyclopropanation/Cope rearrangement reaction of vinylcarbenes with dienes. 相似文献
15.
Lewis Acid Catalyzed Borotropic Shifts in the Design of Diastereo‐ and Enantioselective γ‐Additions of Allylboron Moieties to Aldimines
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Farid W. van der Mei Dr. Hiroshi Miyamoto Daniel L. Silverio Prof. Amir H. Hoveyda 《Angewandte Chemie (International ed. in English)》2016,55(15):4701-4706
Catalytic allylboron additions to aldimines are presented for which small amounts of Zn(OMe)2 serve as the co‐catalyst to accelerate allyl exchange and 1,3‐borotropic shift processes. Low‐yielding and moderately α‐ and diastereoselective reactions are thus turned into highly efficient γ‐, diastereo‐, and enantioselective transformations that exhibit considerable scope. 相似文献
16.
Trialkynyl(vinyl)silanes CH2?CH? Si(C?C? R)3 (R = Bu, Ph, p‐tolyl) were prepared and treated with 9‐borabicyclo[3.3.1]nonane (9‐BBN). Consecutive 1,2‐hydroboration and intramolecular 1,1‐carboboration reactions (each requires different reaction conditions) were studied. 1,2‐Hydroboration of the Si? vinyl group takes place at ambient temperature (23°C in tetrahydrofuran), followed by intramolecular 1,1‐vinylboration to give 1‐silacyclopent‐2‐ene derivatives, bearing still two alkynyl functions at the silicon atom. Further treatment with a second equivalent of 9‐BBN affords 1‐alkenyl‐1‐(alkynyl)‐1‐silacyclopent‐2‐ene derivatives. These undergo intramolecular 1,1‐vinylboration to give 4‐silaspiro[3.4]octa‐1,5‐dienes bearing the boryl groups at 2 and 6 positions. Protodeborylation of all new compounds (intermediates and final products) using acetic acid in slight excess afforded corresponding silanes including spirosilanes. All compounds were characterized using multinuclear NMR spectroscopy (1H, 11B, 13C, 29Si) in solution state. Solid‐state structures for one of the trialkynyl(vinyl)silanes (R = p‐tolyl) and one of the 1‐silacyclopent‐2‐ene derivatives (R = Ph) were confirmed using X‐ray diffraction. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
17.
Catalytic Michael/Ring‐Closure Reaction of α,β‐Unsaturated Pyrazoleamides with Amidomalonates: Asymmetric Synthesis of (−)‐Paroxetine
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Yu Zhang Yuting Liao Prof. Dr. Xiaohua Liu Qian Yao Yuhang Zhou Dr. Lili Lin Prof. Dr. Xiaoming Feng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(42):15119-15124
A highly enantioselective tandem Michael/ring‐closure reaction of α,β‐unsaturated pyrazoleamides and amidomalonates has been accomplished in the presence of a chiral N,N′‐dioxide–Yb(OTf)3 complex (Tf: trifluoromethanesulfonyl) to give various substituted chiral glutarimides with high yields and diastereo‐ and enantioselectivities. Moreover, this methodology could be used for gram‐scale manipulation and was successfully applied to the synthesis of (?)‐paroxetine. Further nonlinear and HRMS studies revealed that the real catalytically active species was a monomeric L ‐PMe2 –Yb3+ complex. A plausible transition state was proposed to explain the origin of the asymmetric induction. 相似文献
18.
Olivier Rousseau Dr. Thierry Delaunay Dr. Geoffroy Dequirez Tran Trieu‐Van Dr. Koen Robeyns Prof. Raphaël Robiette 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(37):12899-12902
A highly enantioselective synthesis of functionalized cyclopentanoids by a formal asymmetric (4+1) annulation strategy was developed. The methodology consists of a stereoselective cyclopropanation reaction between chiral sulfur ylides and 1,3‐dienes followed by a, in situ, stereospecific MgI2‐catalyzed rearrangement of vinylcyclopropanes. This method is distinguished by a remarkable compatibility with functional groups and a high stereocontrol. 相似文献
19.
[2 + 2] Cycloaddition Reactions of Butadienyl Ketene with 1,4‐Diazabuta‐1,3‐dienes: Synthesis of Functionalized Butadienyl‐4‐iminomethyl‐azetidin‐2‐ones and Butenylidene‐butadienyl‐[2,2′‐biazetidine]‐4,4′‐diones
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Deepak Bains Yogesh Kumar Prabhpreet Singh Gaurav Bhargava 《Journal of heterocyclic chemistry》2016,53(5):1665-1669
The reactions of butadienylketene with variety of 1,4‐diazabuta‐1,3‐dienes are studied. The reactions resulted in the formation of previously unknown functionalized cis butadienyl‐4‐iminomethyl‐azetidin‐2‐ones and butenylidene‐butadienyl‐[2,2′‐biazetidine]‐4,4′‐ diones. Butadienyl ketene reacts in [2+2] cycloaddition fashion with both iminic portion of 1,4‐ diazabuta‐1,3‐dienes and competitive [4+2] cycloaddition reaction of 1,4‐diazabuta‐1,3‐dienes as 4π component with butadienyl ketene as 2π component are not observed. 相似文献
20.
Dr. Kazuhiro Okamoto Takuya Shimbayashi Eisuke Tamura Prof. Dr. Kouichi Ohe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(6):1490-1494
This paper describes the development of a palladium‐catalyzed decarboxylative inter‐ and intramolecular condensation reaction of isoxazol‐5(4 H)‐ones with carbonyl compounds in the presence of PPh3, giving various 2‐azabuta‐1,3‐dienes or pyrroles in moderate to high yields. 相似文献